Poor Antibody Response after Two Doses of SARS-CoV-2 vaccine in Transplant Recipients

Clinical application of COVID-19 vaccine in liver transplant recipients

BACKGROUND

Solid organ transplant (SOT) activities, such as liver transplant, have been greatly influenced by the pandemic of coronavirus disease 2019 (COVID-19), a disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Immunosuppressed individuals of liver transplant recipients (LTRs) tend to have a high risk of COVID-19 infection and related complications. Therefore, COVID-19 vaccination has been recommended to be administered as early as possible in LTRs.

DATA SOURCES

The keywords "liver transplant", "SARS-CoV-2", and "vaccine" were used to retrieve articles published in PubMed.

RESULTS

The antibody response following the 1st and 2nd doses of vaccination was disappointingly low, and the immune responses among LTRs remarkably improved after the 3rd or 4th dose of vaccination. Although the 3rd or 4th dose of COVID-19 vaccine increased the antibody titer, a proportion of patients remained unresponsive. Furthermore, recent studies showed that SARS-CoV-2 vaccine could trigger adverse events in LTRs, including allograft rejection and liver injury.

CONCLUSIONS

This review provides the recently reported data on the antibody response of LTRs following various doses of vaccine, risk factors for poor serological response and adverse events after vaccination.

Assessing antiviral treatment efficacy and risk factors for severe COVID-19 in kidney transplant recipients during the Omicron subvariant-dominant period: a retrospective study

BACKGROUND

Kidney transplant recipients (KTRs) are at risk of severe coronavirus disease 2019 (COVID-19), and even now that Omicron subvariants have become dominant, cases of severe disease are certain to occur. The aims of this retrospective study were to evaluate the efficacy of antiviral treatment for COVID-19 and to identify risk factors for severe disease in KTRs during Omicron subvariant-dominant periods.

METHODS

A total of 65 KTRs diagnosed with COVID-19 who received antiviral treatment between July 2022 and September 2023 were analyzed. Mild cases received oral molnupiravir (MP) as outpatient therapy, while moderate or worse cases received intravenous remdesivir (RDV) as inpatient therapy. In principle, mycophenolate mofetil was withdrawn and switched to everolimus. We investigated the efficacy of antiviral treatment and compared the clinical parameters of mild/moderate and severe/critical cases to identify risk factors for severe COVID-19.

RESULTS

Among 65 cases, 49 were mild, 6 were moderate, 9 were severe, and 1 was of critical severity. MP was administered to 57 cases; 49 (86%) improved and 8 (14%) progressed. RDV was administered to 16 cases; 14 (87%) improved and 2 (13%) progressed. Seventeen (26%) cases required hospitalization, and none died. Comparisons of the severe/critical group (n = 10) with the mild/moderate group (n = 55) demonstrated that the severe/critical group had a significantly higher median age (64 vs. 53 years, respectively; p = 0.0252), prevalence of diabetes (70% vs. 22%, respectively; p = 0.0047) and overweight/obesity (40% vs. 11%, respectively; p = 0.0393), as well as a significantly longer median time from symptom onset to initial antiviral therapy (3 days vs. 1 day, respectively; p = 0.0026). Multivariate analysis showed that a longer time from symptom onset to initial antiviral treatment was an independent risk factor for severe COVID-19 (p = 0.0196, odds ratio 1.625, 95% confidence interval 1.081-2.441).

CONCLUSION

These findings suggest that a longer time from symptom onset to initial antiviral treatment is associated with a higher risk of severe COVID-19 in KTRs. Initiating antiviral treatment as early as possible is crucial for preventing severe outcomes; this represents a valuable insight into COVID-19 management in KTRs.

Factors associated with IgG titers against SARS-CoV-2 spike protein after second vaccination in people living with HIV controlled with anti-retroviral therapy

OBJECTIVE

This study aimed to identify factors associated with the response to the SARS-CoV-2 vaccine in people living with HIV (PLWH).

METHODS

This study was conducted at the Jikei University School of Medicine, Tokyo, Japan. IgG antibodies against spike and nucleocapsid proteins were detected using Abbott SARS-CoV-2 IgG II Quant assays.

RESULTS

During the investigation period, 371 PLWH were enrolled in this study. PLWH with previous COVID-19 infection, untreated or poorly controlled HIV infection, and those whose blood samples were obtained within less than seven days after the second vaccination were excluded. A total of 310 PLWH controlled with anti-retroviral therapy were included in the final analysis. Multivariate analysis demonstrated that chronic kidney disease (CKD) (β = -0.353, p = 0.049) and the duration between the second vaccination and blood sampling (β = -0.005, p < 0.001) were associated with low spike protein IgG titers.

CONCLUSION

Even without hemodialysis or kidney transplant, CKD was associated with vaccine response in PLWH.

Impaired neutralizing antibody efficacy of tixagevimab-cilgavimab 150+150 mg as pre-exposure prophylaxis against Omicron BA.5. A real-world experience in booster vaccinated immunocompromised patients

BACKGROUND

Tixagevimab-cilgavimab has been approved as primary pre-exposure prophylaxis in immunocompromised patients as support or replacement for vaccination, even though the Omicron variant of concern (VOC) was spreading at the time.

OBJECTIVES

The aim of our study was to evaluate the post-injection neutralising activity (NT90-Abs titre) against the Omicron BA.5 variant in fully vaccinated immunocompromised patients.

STUDY DESIGN

NT90-Abs titres against BA.5 and 20A.EU1 as well as anti-spike and anti-receptor-binding domain IgG were evaluated 0, 14, and 30 d after tixagevimab-cilgavimab administration. The primary end point was NT90-Abs titres ≥ 80 against BA.5 in ≥ 25% of patients, and the secondary end point was NT90-Abs titres ≥ 1280 against 20A.EU1 in >50% of patients on day 14.

RESULTS

At baseline, 35.2%, 37.02%, and 32.5% of booster vaccinated patients exhibited undetectable levels of anti-S and anti-RBD IgG antibodies such as NT90-Abs titres against A20.EU1. Moreover, 35 patients (61.5%) had undetectable NT90-Abs titres against BA.5. On day 14, IgG anti-S and anti-RBD levels were 3880 BAU/mL and 776.6 AU/mL, respectively. Only 12.5% of patients met a NT90-Abs titres ≥ 80 against BA.5, whereas the median NT90-Abs titre against 20A.EU1 was 1280. NT90-Abs titres against BA.5 were 64-fold lower than those against A20.EU1. Four patients (7.5%) had a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the 3 months after treatment, all with a time gap between the booster vaccination and injection.

CONCLUSIONS

To date, tixagevimab-cilgavimab cannot be considered a substitute for vaccination but may be a useful supporting therapy if the recommended dose for pre-exposure prophylaxis is doubled.

Comparison of BNT162b2 and mRNA1273 vaccines in solid organ transplant recipients: Post-Hoc analysis of a Japanese national prospective study

The coronavirus disease-19 (COVID-19) vaccine efficacy and immunogenicity in the immunocompetent population are well established. However, in solid organ transplant (SOT) recipients, because of their use of immunosuppressive medication, the immunogenicity of these severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines remains suboptimal. Both BNT162b2 and mRNA1273 have been used for some time, but their immunogenicity has not been directly compared in this immunocompromised patient group. We performed a post-hoc analysis of a previous prospective cohort study. The inclusion criteria were adult SOT recipients with active grafts at least 1 month after SOT. After giving consent, participants chose to receive either BNT162b2 or mRNA1273 vaccine. Anti-spike-protein-S antibody against SARS-CoV-2 was measured. Propensity scores were calculated via logistic regression to transform the probability of having received either BNT162b2 or mRNA1273 vaccine, and a model was developed. We enrolled 623 SOT recipients. In the propensity score-matched analysis, 100 recipients were selected for BNT162b2 and 100 for mRNA1273. SARS-CoV-2 anti-spike protein antibody positivity with BNT162b2 versus mRNA1273 at 3 weeks after the first dose, 1 month after the second dose, 3 months after the second dose, and 6 months after the second dose were 10% versus 19% (P = .07), 51% versus 58% (P = .30), 74% versus 88% (P = .01), and 78% versus 87% (P = .13), respectively. We conducted a propensity score-matched comparison of BNT162b2 and mRNA1273 vaccines as the primary series of COVID-19 vaccines in SOT recipients. We found significantly better immunogenicity with the mRNA1273 vaccine than with BNT162b2.

Factors influencing immunogenicity and safety of SARS-CoV-2 vaccine in liver transplantation recipients: a systematic review and meta-analysis

Background

This review summarizes the factors influencing the efficacy and safety of the COVID-19 vaccine in LTR through meta-analysis, hoping to provide strategies for vaccine use.

Methods

Electronic databases were screened for studies on mRNA vaccines in LTR. The primary outcome was the pooled seroconversion rate, and the secondary outcome was the incidence of adverse events+breakthrough infections. Subgroup analyses were made based on BMI, associated comorbidities, presence of baseline leukopenia, time since transplant, and drugs used.

Result

In total, 31 articles got included. The pooled seroconversion rate after at least two doses of SARS-CoV-2 vaccination was 72% (95% CI [0.52-0.91). With significant heterogeneity among studies I2 = 99.9%, the seroconversion rate was about 72% (95%CI [0.66-0.75]), from the studies reporting two doses of vaccine slightly higher around 75%(95%CI [0.29-1.22]) from studies reporting three doses. The pooled seroconversion rate within the lower to normal BMI group was 74% (95% CI [0.22-1.27], Pi=0.005) against 67% (95% CI [0.52-0.81], Pi=0.000) in the high BMI group. The pooled seroconversion rate in the ''positive leukopenia'' group was the lowest, 59%. Leukopenia could influence the vaccine seroconversion rate in LTR. From the time since transplant analysis after setting seven years as cut off point, the pooled seroconversion rate after at least two doses of COVID-19 vaccination was 53% (95% CI [0.18-0.83], P=0.003, I2 = 99.6%) in <7years group and 83% (95% CI [0.76-0.90], P=0.000 I2 = 95.7%) in > 7years group. The only time since transplantation had reached statistical significance to be considered a risk factor predictor of poor serological response (OR=1.27 95%CI [1.03-1.55], P=0.024). The breakthrough infection rate after vaccination was very low2% (95% CI 0.01-0.03, I2 = 63.0%), and the overall incidence of adverse events, which included mainly pain at the injection site and fatigue, was 18% (95%CI [0.11-0.25], I2 = 98.6%, Pi=0.000).

Conclusion

The seroconversion rate in LTR vaccinated with at least two doses of mRNA COVID-19 vaccine could be significantly affected by the vaccine type, immunosuppressant used, BMI, leukopenia, associated comorbidities, and time since transplantation. Nevertheless, booster doses are still recommended for LTR.

Impact and management of COVID-19 in liver transplant candidates and recipients

The COVID-19 outbreak has had severe consequences for global public health, medical communities, and the socioeconomic status of a considerable number of countries. The emergence of COVID-19 has also significantly impacted the world of liver transplantation (LT). Studies from transplantation centers around the world have shown that LTs during the COVID-19 pandemic have been restricted because of the high risk of serious COVID-19 infection in this population. According to the Centers for Disease Control and Prevention, patients with liver disease are considered at higher risk for severe COVID-19 infection. In March 2020, the American Association for the Study of Liver Diseases recommended that LT should be limited to emergency cases. The COVID-19 treatment guidelines published by the National Institutes of Health are being constantly updated according to new epidemiology trends and treatment regimens. Immunocompromised patients have a higher risk of developing severe disease or death from COVID-19 compared with the general population. In this review, we summarize the available evidence regarding treatment guidelines and considerations for the evaluation and management of LT candidates and recipients in the era of COVID-19. In addition, we present data regarding COVID-19 among LT patients in our local transplantation center.

Susceptibility to SARS-CoV-2 Infection and Immune Responses to COVID-19 Vaccination Among Recipients of Solid Organ Transplants

Solid organ transplant recipients (SOTRs) are at high risk for infections including SARS-CoV-2, primarily due to use of immunosuppressive therapies that prevent organ rejection. Furthermore, these immunosuppressants are typically associated with suboptimal responses to vaccination. While COVID-19 vaccines have reduced the risk of COVID-19-related morbidity and mortality in SOTRs, breakthrough infection rates and death remain higher in this population compared with immunocompetent individuals. Approaches to enhancing response in SOTRs, such as through administration of additional doses and heterologous vaccination, have resulted in increased seroresponse and antibody levels. In this article, safety and immunogenicity of mRNA COVID-19 vaccines in SOTRs are explored by dose. Key considerations for clinical practice and the current vaccine recommendations for SOTRs are discussed within the context of the dynamic COVID-19 vaccination guideline landscape. A thorough understanding of these topics is essential for determining public health and vaccination strategies to help protect immunocompromised populations, including SOTRs.

Effects of Sirolimus Treatment on Fetal Hemoglobin Production and Response to SARS-CoV-2 Vaccination: A Case Report Study

The β-thalassemias are a group of monogenic hereditary hematological disorders caused by deletions and/or mutations of the β-globin gene, leading to low or absent production of adult hemoglobin (HbA). For β-thalassemia, sirolimus has been under clinical consideration in two trials (NCT03877809 and NCT04247750). A reduced immune response to anti-SARS-CoV-2 vaccination has been reported in organ recipient patients treated with the immunosuppressant sirolimus. Therefore, there was some concern regarding the fact that monotherapy with sirolimus would reduce the antibody response after SARS-CoV-2 vaccination. In the representative clinical case reported in this study, sirolimus treatment induced the expected increase of fetal hemoglobin (HbF) but did not prevent the production of anti-SARS-CoV-2 IgG after vaccination with mRNA-1273 (Moderna). In our opinion, this case report should stimulate further studies on β-thalassemia patients under sirolimus monotherapy in order to confirm the safety (or even the positive effects) of sirolimus with respect to the humoral response to anti-SARS-CoV-2 vaccination. In addition, considering the extensive use of sirolimus for the treatment of other human pathologies (for instance, in organ transplantation, systemic lupus erythematosus, autoimmune cytopenia, and lymphangioleiomyomatosis), this case report study might be of general interest, as large numbers of patients are currently under sirolimus treatment.

The Cellular and Humoral Immune Response to SARS-CoV-2 Messenger RNA Vaccines Is Significantly Better in Liver Transplant Patients Compared with Kidney Transplant Patients

Patients after organ transplantation have impaired immune response after vaccination against the SARS-CoV-2 virus. So far, published studies have reported quite different response rates to SARS-CoV-2 vaccination, ranging from 15-79% in liver and kidney transplant recipients. Up to one year after the first vaccine dose, we analyzed the humoral and cellular immune response of 21 liver transplant (LTX) patients after vaccination with mRNA vaccines compared with 28 kidney transplant (KTX) patients. We evaluated IgG against the SARS-CoV-2 spike protein as well as SARS-CoV-2 specific T cells using an ELISpot assay that detected IFN-γ- and/or IL-2-expressing T cells. We found a cellular and/or humoral immune response in 100% of the LTX patients compared with 68% of the KTX patients. Antibody titers against the spike protein of SARS-CoV-2 were significantly higher in the LTX group, and significantly more LTX patients had detectable specific IL-2-producing T cells. The immunosuppression applied in our LTX cohort was lower compared with the KTX cohort (14% triple therapy in LTX patients vs. 79% in KTX patients). One year after the first vaccination, breakthrough infections could be detected in 41% of all organ transplant patients. None of those patients suffered from a severe course of COVID-19 disease, indicating that a partial vaccination response seemed to offer protection to immunosuppressed patients. The better immune response of LTX patients after SARS-CoV-2 vaccination might be due to less intense immunosuppressive therapy compared with KTX patients.

Humoral and Cellular Immunity following Five Doses of COVID-19 Vaccines in Solid Organ Transplant Recipients: A Systematic Review and Meta-Analysis

Solid organ transplant (SOT) recipients are at increased risk of COVID-19 infection because of their suppressed immunity. The available data show that COVID-19 vaccines are less effective in SOT recipients. We aimed to assess the cellular and humoral immunogenicity with an increasing the number of doses of COVID-19 vaccines in SOT recipients and to identify factors affecting vaccine response in this population. A systematic review and meta-analysis were conducted to identify ongoing and completed studies of humoral and cellular immunity following COVID-19 vaccines in SOT recipients. The search retrieved 278 results with 45 duplicates, and 43 records did not match the inclusion criteria. After title and abstract screening, we retained 189 records, and 135 records were excluded. The reasons for exclusion involved studies with immunocompromised patients (non-transplant recipients), dialysis patients, and individuals who had already recovered from SARS-CoV-2 infection. After full-text reading, 55 observational studies and randomized clinical trials (RCTs) were included. The proportion of responders appeared higher after the third, fourth, and fifth doses. The risk factors for non-response included older age and the use of mycophenolate mofetil, corticosteroids, and other immunosuppressants. This systematic review and meta-analysis demonstrates the immunogenicity following different doses of COVID-19 vaccines among SOT patients. Due to the low immunogenicity of vaccines, additional strategies to improve vaccine response may be necessary.

Serological Responses after a Fourth Dose of SARS-CoV-2 Vaccine in Solid Organ Transplant Recipients: A Systematic Review and Meta-Analysis

The humoral immune response and safety of the fourth dose of the coronavirus disease 2019 (COVID-19) vaccine in solid organ transplant (SOT) recipients need to be fully elucidated. We conducted a systematic review and meta-analysis to assess the efficacy and safety associated with this additional dose of the COVID-19 vaccine in the SOT recipients. A comprehensive search was conducted to identify studies on SOT patients without prior natural SARS-CoV-2 infection who received the fourth dose of the COVID-19 vaccine. Serological antibody responses following vaccination were synthesized by a meta-analysis of proportions. The proportions for each outcome were integrated by using a random-effects model. Approximately 56-92% of the SOT patients developed a humoral immune response, and the pooled seroprevalence rate was 75% (95% confidence interval [CI], 62-82%) after administering the third vaccine dose. Following the fourth dose of vaccination, approximately 76-95% of the patients developed a humoral immune response. The pooled seroprevalence rate after the fourth dose was 85% (95% CI, 79-91%). Of the patients who initially tested seronegative after the second dose, approximately 22-76% of patients subsequently became seropositive after the third dose. The pooled seroconversion rate for the third dose was 47% (95% CI, 31-64%). Among the patients who were seronegative after the third dose, approximately 25-76% turned seropositive after the fourth dose. The pooled seroconversion rate after the fourth dose was 51% (95% CI, 40-63%). Safety data were reported in three studies, demonstrating that adverse effects following the fourth dose were generally mild, and patients with these adverse effects did not require hospitalization. No transplant rejection or serious adverse events were observed. A fourth dose of the COVID-19 vaccine in SOT recipients was associated with an improved humoral immune response, and the vaccine was considered relatively safe.

Immunogenicity, Safety, and Breakthrough Severe Acute Respiratory Syndrome Coronavirus 2 Infections After Coronavirus Disease 2019 Vaccination in Organ Transplant Recipients: A Prospective Multicenter Canadian Study

Background

Solid organ transplant (SOT) recipients are at risk for severe coronavirus disease 2019 (COVID-19), despite vaccination. Our study aimed to elucidate COVID-19 vaccine immunogenicity and evaluate adverse events such as hospitalization, rejection, and breakthrough infection in a SOT cohort.

Methods

We performed a prospective, observational study on 539 adult SOT recipients (age ≥18 years old) recruited from 7 Canadian transplant centers. Demographics including transplant characteristics, vaccine types, and immunosuppression and events such as hospitalization, infection, and rejection were recorded. Follow ups occurred every 4-6 weeks postvaccination and at 6 and 12 months from first dose. Serum was processed from whole blood to measure anti-receptor binding domain (RBD) antibodies of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein to assess immunogenicity.

Results

The COVID-19 vaccines were found to be safe in SOT recipients with low rates of rejection requiring therapy (0.7%). Immunogenicity improved after the third vaccine dose, yet 21% developed no anti-RBD response. Factors such as older age, lung transplantation, chronic kidney disease, and shorter duration from transplant were associated with decreased immunogenicity. Patients with at least 3 doses were protected from hospitalization when experiencing breakthrough infections. Significantly increased anti-RBD levels were observed in patients who received 3 doses and had breakthrough infection.

Conclusions

Three or four doses of COVID-19 vaccines were safe, increased immunogenicity, and protected against severe disease requiring hospitalization. Infection paired with multiple vaccinations significantly increased anti-RBD response. However, SOT populations should continue to practice infection prevention measures, and they should be prioritized for SARS-CoV-2 pre-exposure prophylactics and early therapeutics.

Durability of Immune Response after Application of a Third Dose of SARS-CoV-2 Vaccination in Liver Transplant Recipients

Immunogenicity after SARS-CoV-2 vaccination is known to be impaired in liver transplant (LT) recipients, but the results after the application of a third dose show significant improvement in seroconversion rates. In the general population, the antibody response wanes over the course of time after two doses of the vaccination, but seems to be more robust after the application of three doses. Still, the durability of the antibody response in LT recipients who receive a third dose of SARS-CoV-2 vaccination has not been analyzed yet. We therefore assessed antibody responses in a total of 300 LT recipients and observed antibody titers for six months each after patients had received the second and the third doses of the vaccination, explicitly excluding all patients who had suffered from SARS-CoV-2 infection. The initial antibody response was compared to a control group of 122 healthcare workers. After the application of two doses of the vaccination, 74% of LT recipients (158 out of 213) developed antibodies against SARS-CoV-2; this result depended significantly on whether the patients were taking the medication mycophenolate mofetil, and on the age of the patients. Antibody titers declined significantly within six months from 407 BAU/mL (IQR: 0–1865) to 105 BAU/mL (IQR: 0–145) (p ≤ 0.001), but increased after the application of the third vaccine dose in 92% of patients (105 out of 114), showing an antibody response (p ≤ 0.001). After a further six-month period, despite showing a decline from 2055 BAU/mL (IQR: 500 to >2080) to 1805 BAU/mL (IQR: 517 to >2080), the waning of antibody titers was not significant (p = 0.706), and antibody durability appeared to be more robust than that after the second dose. In conclusion, our study confirms the high efficacy of the application of a third dose of SARS-CoV-2 vaccination in LT recipients, and a reasonably sustained humoral response with superior durability in comparison to antibody kinetics after the application of the second dose of the vaccination.

Clinical Outcomes of SARS-CoV-2 Breakthrough Infections in Liver Transplant Recipients during the Omicron Wave

At the start of the pandemic, liver transplant recipients (LTR) were at high risk of developing severe COVID-19. Here, the outcomes of breakthrough infections in fully vaccinated LTR (n = 98) during the Omicron wave were assessed. In most patients, a mild disease course was observed, but 11 LTR (11.2%) required hospitalization for COVID-19-related complications. All patients survived. The LTR requiring hospitalization were older (67 years vs. 54 years; p < 0.001), had a higher Charlson comorbidity index (9 vs. 5; p < 0.001), and a lower anti-S RBD titer (Roche Elecsys) prior to infection (508.3 AU/mL vs. 2044 AU/mL; p = 0.03). Long-lasting symptoms for ≥4 weeks were reported by 37.5% of LTR (30/80). Risk factors in LTR included female sex (p = 0.01; Odds Ratio (OR) = 4.92 (95% confidence interval (CI) (1.5-16.5)) and dyspnea (p = 0.009; OR = 7.2 (95% CI (1.6-31.6)) during infection. Post-infection high anti-S RBD antibody levels were observed in LTR, and healthy controls (HC), while the cellular immune response, assessed by interferon-gamma release assay (EUROIMMUN), was significantly lower in LTR compared with HC (p < 0.001). In summary, in fully vaccinated LTR, SARS-CoV-2 breakthrough infections during the Omicron wave led to mild disease courses in the majority of patients and further boosted the humoral and cellular hybrid anti-SARS-CoV-2-directed immune response. While all patients survived, older and multimorbid LTR with low baseline antibody titers after vaccination still had a substantial risk for a disease course requiring hospitalization due to COVID-19-related complications.

Immunogenicity of Inactivated SARS-CoV-2 Vaccine (BBIBP-CorV; Sinopharm) and Short-Term Clinical Outcomes in Vaccinated Solid Organ Transplant Recipients: A Prospective Cohort Study

BackgroundImmunocompromised patients have lower seroconversion rate in response to COVID-19 vaccination. The aim of this study is to evaluate the humoral immune response with short-term clinical outcomes in solid organ transplant recipients vaccinated with SARS-CoV-2 vaccine (BBIBP-CorV; Sinopharm).MethodsThis prospective cohort was conducted from March to December 2021 in Abu Ali Sina hospital, Iran. All transplant recipients, older than 18 years were recruited. The patients received two doses of Sinopharm vaccine 4 weeks apart. Immunogenicity was evaluated through assessment of antibodies against the receptor-binding domain (RBD) of SARS-CoV-2 after the first and second dose of vaccine. The patients were followed up for 6 months after vaccination.ResultsOut of 921 transplant patients, 115 (12.5%) and 239 (26%) had acceptable anti S-RBD immunoglobulin G (IgG) levels after the first and second dose, respectively. Eighty patients (8.68%) got infected with COVID-19 which led to 45 (4.9%) of patients being hospitalized. None of the patients died during follow-up period. Twenty-four (10.9%) liver transplant recipients developed liver enzyme elevation, and increased serum creatinine was observed in 86 (13.5%) kidney transplant patients. Two patients experienced biopsy-proven rejection without any graft loss.ConclusionOur study revealed that humoral response rate of solid organ transplant recipients to Sinopharm vaccine was low.

COVID-19 mortality may be reduced among fully vaccinated solid organ transplant recipients

BACKGROUND

Solid organ transplant (SOT) recipients are at increased risk for morbidity and mortality from COVID-19 due to their immunosuppressed state and reduced immunogenicity from COVID-19 mRNA vaccines. This investigation examined the association between COVID-19 mRNA vaccination status and mortality among SOT recipients diagnosed with COVID-19.

METHODS & FINDINGS

A retrospective, registry-based chart review was conducted investigating COVID-19 mortality among immunosuppressed solid organ transplant (SOT) recipients in a large metropolitan healthcare system in Houston, Texas, USA. Electronic health record data was collected from consecutive SOT recipients who received a diagnostic SARS-CoV-2 test between March 1, 2020, and October 1, 2021. The primary exposure was COVID-19 vaccination status at time of COVID-19 diagnosis. Patients were considered 'fully vaccinated' at fourteen days after completing their vaccine course. COVID-19 mortality within 60 days and intensive care unit admission within 30 days were primary and secondary endpoints, respectively. Among 646 SOT recipients who were diagnosed with COVID-19 at Houston Methodist Hospital between March 2020, and October 2021, 70 (10.8%) expired from COVID-19 within 60 days. Transplanted organs included 63 (9.8%) heart, 355 (55.0%) kidney, 108 (16.7%) liver, 70 (10.8%) lung, and 50 (7.7%) multi-organ. Increasing age was a risk factor for COVID-19 mortality, while vaccination within 180 days of COVID-19 diagnosis was protective in Cox proportional hazard models with hazard ratio 1.04 (95% CI: 1.01-1.06) and 0.31 (0.11-0.90), respectively). These findings were confirmed in the propensity score matched cohort between vaccinated and unvaccinated patients.

CONCLUSIONS

This investigation found COVID-19 mortality may be significantly reduced among immunosuppressed SOT recipients within 6 months following vaccination. These findings can inform vaccination policies targeting immunosuppressed populations worldwide.

Humoral and cellular response of COVID-19 vaccine among solid organ transplant recipients: A systematic review and meta-analysis

BACKGROUND

We aimed to analyze the humoral and cellular response to standard and booster (additional doses) COVID-19 vaccination in solid organ transplantation (SOT) and the risk factors involved for an impaired response.

METHODS

We did a systematic review and meta-analysis of studies published up until January 11, 2022, that reported immunogenicity of COVID-19 vaccine among SOT. The study is registered with PROSPERO, number CRD42022300547.

RESULTS

Of the 1527 studies, 112 studies, which involved 15391 SOT and 2844 healthy controls, were included. SOT showed a low humoral response (effect size [ES]: 0.44 [0.40-0.48]) in overall and in control studies (log-Odds-ratio [OR]: -4.46 [-8.10 to -2.35]). The humoral response was highest in liver (ES: 0.67 [0.61-0.74]) followed by heart (ES: 0.45 [0.32-0.59]), kidney (ES: 0.40 [0.36-0.45]), kidney-pancreas (ES: 0.33 [0.13-0.53]), and lung (0.27 [0.17-0.37]). The meta-analysis for standard and booster dose (ES: 0.43 [0.39-0.47] vs. 0.51 [0.43-0.54]) showed a marginal increase of 18% efficacy. SOT with prior infection had higher response (ES: 0.94 [0.92-0.96] vs. ES: 0.40 [0.39-0.41]; p-value < .01). The seroresponse with mRNA-12723 mRNA was highest 0.52 (0.40-0.64). Mycophenolic acid (OR: 1.42 [1.21-1.63]) and Belatacept (OR: 1.89 [1.3-2.49]) had highest risk for nonresponse. SOT had a parallelly decreased cellular response (ES: 0.42 [0.32-0.52]) in overall and control studies (OR: -3.12 [-0.4.12 to -2.13]).

INTERPRETATION

Overall, SOT develops a suboptimal response compared to the general population. Immunosuppression including mycophenolic acid, belatacept, and tacrolimus is associated with decreased response. Booster doses increase the immune response, but further upgradation in vaccination strategy for SOT is required.

COVID-19 and liver disease

Knowledge on SARS-CoV-2 infection and its resultant COVID-19 in liver diseases has rapidly increased during the pandemic. Hereby, we review COVID-19 liver manifestations and pathophysiological aspects related to SARS-CoV-2 infection in patients without liver disease as well as the impact of COVID-19 in patients with chronic liver disease (CLD), particularly cirrhosis and liver transplantation (LT). SARS-CoV-2 infection has been associated with overt proinflammatory cytokine profile, which probably contributes substantially to the observed early and late liver abnormalities. CLD, particularly decompensated cirrhosis, should be regarded as a risk factor for severe COVID-19 and death. LT was impacted during the pandemic, mainly due to concerns regarding donation and infection in recipients. However, LT did not represent a risk factor per se of worse outcome. Even though scarce, data regarding COVID-19 specific therapy in special populations such as LT recipients seem promising. COVID-19 vaccine-induced immunity seems impaired in CLD and LT recipients, advocating for a revised schedule of vaccine administration in this population.

COVID-19 Vaccination in Kidney Transplant Candidates and Recipients

Kidney transplant candidates and kidney transplant recipients (KTRs) are at particular risk of severe complications of COVID-19 disease. In Western countries, mortality in affected hospitalized KTRs ranges between 19% and 50%. COVID-19 vaccination remains the most important measure to prevent the severity of infection in candidates and recipients of kidney transplant. However, the uraemic condition may affect the vaccine-induced immunity in patients with advanced chronic kidney disease (CKD) and in KTRs. Retention of uraemic toxins, dysbiosis, dysmetabolism, and dialysis can diminish the normal response to vaccination, leading to dysfunction of inflammatory and immune cells. In KTRs the efficacy of vaccines may be reduced by the immunosuppressive medications, and more than half of kidney transplant recipients are unable to build an immune response even after four administrations of anti-COVID-19 vaccines. The lack of antibody response leaves these patients at high risk for SARS-CoV-2 infection and severe COVID-19 disease. The aim of the present review is to focus on the main reasons for the impaired immunological response among candidates and kidney transplant recipients and to highlight some of the present options available to solve the problem.

Association between immunosuppressants and poor antibody responses to SARS-CoV-2 vaccines in patients with autoimmune liver diseases

The antibody and B cell responses after inactivated SARS-CoV-2 vaccination have not been well documented in patients with autoimmune liver disease (AILD). Therefore, we conducted a prospective observational study that included AILD patients and healthy participants as controls between July 1, 2021, and September 30, 2021, at the Second Affiliated Hospital of Chongqing Medical University. All adverse events (AEs) after the COVID-19 vaccination were recorded and graded. Immunoglobulin (Ig)-G antibodies against the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein (anti-RBD-IgG) and neutralizicadng antibodies (NAbs) were tested following full-course vaccination (BBIBP-CorV or CoronaVac). In addition, SARS-CoV-2-specific B cells were detected by flow cytometry. In total, 76 AILD patients and 136 healthy controls (HCs) were included. All AEs were mild and self-limiting, and the incidences were similar between the AILD and HCs. The seropositivity rates of anti-RBD-IgG and NAbs in AILD were 97.4% (100% in HCs, p = 0.13) and 63.2% (84.6% in HCs, p < 0.001), respectively. The titers of anti-RBD-IgG and NAbs were significantly lower in AILD patients than those in HCs. After adjusting for confounders, immunosuppressive therapy was an independent risk factor for low-level anti-RBD-IgG (adjusted odds ratio [aOR]: 4.7; 95% confidence interval [CI], 1.5-15.2; p = 0.01) and a reduced probability of NAbs seropositivity (aOR, 3.0; 95% CI, 1.0-8.9; p = 0.04) in AILD patients. However, regardless of immunosuppressants, the SARS-CoV-2-specific memory B cells responses were comparable between the AILD and HC groups. Our results suggest that inactivated SARS-CoV-2 vaccines (BBIBP-CorV and CoronaVac) are safe, but their immunogenicity is compromised in patients with AILD. Moreover, immunosuppressants are significantly associated with poor antibody responses to the SARS-CoV-2 vaccines. These results could inform physicians and policymakers about decisions on screening the populations at higher risk of poor antibody responses to SARS-CoV-2 vaccines and providing additional vaccinations in patients with AILD.

Predicting a Positive Antibody Response After 2 SARS-CoV-2 mRNA Vaccines in Transplant Recipients: A Machine Learning Approach With External Validation

BACKGROUND

Solid organ transplant recipients (SOTRs) are less likely to mount an antibody response to SARS-CoV-2 mRNA vaccines. Understanding risk factors for impaired vaccine response can guide strategies for antibody testing and additional vaccine dose recommendations.

METHODS

Using a nationwide observational cohort of 1031 SOTRs, we created a machine learning model to explore, identify, rank, and quantify the association of 19 clinical factors with antibody responses to 2 doses of SARS-CoV-2 mRNA vaccines. External validation of the model was performed using a cohort of 512 SOTRs at Houston Methodist Hospital.

RESULTS

Mycophenolate mofetil use, a shorter time since transplant, and older age were the strongest predictors of a negative antibody response, collectively contributing to 76% of the model's prediction performance. Other clinical factors, including transplanted organ, vaccine type (mRNA-1273 versus BNT162b2), sex, race, and other immunosuppressants, showed comparatively weaker associations with an antibody response. This model showed moderate prediction performance, with an area under the receiver operating characteristic curve of 0.79 in our cohort and 0.67 in the external validation cohort. An online calculator based on our prediction model is available at http://transplantmodels.com/covidvaccine/ .

CONCLUSIONS

Our machine learning model helps understand which transplant patients need closer follow-up and additional doses of vaccine to achieve protective immunity. The online calculator based on this model can be incorporated into transplant providers' practice to facilitate patient-centric, precision risk stratification and inform vaccination strategies among SOTRs.

COVID-19 vaccine immunogenicity among chronic liver disease patients and liver transplant recipients: A meta-analysis

BACKGROUND/AIMS

Data of coronavirus disease 2019 (COVID-19) vaccine immunogenicity among chronic liver disease (CLD) and liver transplant (LT) patients are conflicting. We performed meta-analysis to examine vaccine immunogenicity regarding etiology, cirrhosis status, vaccine platform and type of antibody.

METHODS

We collected data via three databases from inception to February 16, 2022, and reported pooled seroconversion rate, T cell response and safety data after two vaccine doses.

RESULTS

Twenty-eight (CLD only: 5; LT only: 18; both: 2; LT with third dose: 3) observational studies of 3,945 patients were included. For CLD patients, seroconversion rate ranged between 84% (95% confidence interval [CI], 76-90%) and 91% (95% CI, 83-95%), based predominantly on neutralizing antibody and anti-spike antibody, respectively. Seroconversion rate was 81% (95% CI, 76-86%) in chronic hepatitis B, 96% (95% CI, 93-97%) in non-alcoholic fatty liver disease, 85% (95% CI, 75-91%) in cirrhosis and 85% (95% CI, 78-90%) in non-cirrhosis, 86% (95% CI, 78-92%) for inactivated vaccine and 89% (95% CI, 71-96%) for mRNA vaccine. The pooled seroconversion rate of anti-spike antibody was 66% (95% CI, 55-75%) after two doses of mRNA vaccines and 88% (95% CI, 58-98%) after third dose among LT recipients. T cell response rate was 65% (95% CI, 30-89%). Prevalence of adverse events was 27% (95% CI, 18-38%) and 63% (95% CI, 39-82%) among CLD and LT groups, respectively.

CONCLUSION

CLD patients had good humoral response to COVID-19 vaccine, while LT recipients had lower response.

Liver transplantation during COVID-19: Adaptive measures with future significance

Following the outbreak of coronavirus disease 2019 (COVID-19), a disease caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the field of liver transplantation, along with many other aspects of healthcare, underwent drastic changes. Despite an initial increase in waitlist mortality and a decrease in both living and deceased donor liver transplantation rates, through the implementation of a series of new measures, the transplant community was able to recover by the summer of 2020. Changes in waitlist prioritization, the gradual implementation of telehealth, and immunosuppressive regimen alterations amidst concerns regarding more severe disease in immunocompromised patients, were among the changes implemented in an attempt by the transplant community to adapt to the pandemic. More recently, with the advent of the Pfizer BNT162b2 vaccine, a powerful new preventative tool against infection, the pandemic is slowly beginning to subside. The pandemic has certainly brought transplant centers around the world to their limits. Despite the unspeakable tragedy, COVID-19 constitutes a valuable lesson for health systems to be more prepared for potential future health crises and for life-saving transplantation not to fall behind.

Immunogenicity of COVID-19 vaccines in chronic liver disease patients and liver transplant recipients: A systematic review and meta-analysis

BACKGROUND AND AIMS

Chronic liver disease (CLD) patients and liver transplant (LT) recipients have an increased risk of morbidity and mortality from coronavirus disease 2019 (COVID-19). The immunogenicity of COVID-19 vaccines in CLD patients and LT recipients is poorly understood. The present study aimed to evaluate the immunogenicity of COVID-19 vaccines in CLD patients and LT recipients.

METHODS

We searched electronic databases for eligible studies. Two reviewers independently conducted the literature search, extracted the data and assessed the risk of bias of included studies. The rates of detectable immune response were pooled from single-arm studies. For comparative studies, we compared the rates of detectable immune response between patients and healthy controls. The meta-analysis was conducted using the Stata software with a random-effects model.

RESULTS

In total, 19 observational studies involving 4191 participants met the inclusion criteria. The pooled rates of detectable humoral immune response after two doses of COVID-19 vaccination in CLD patients and LT recipients were 95% (95% confidence interval [CI] = 88%-99%) and 66% (95% CI = 57%-74%) respectively. After two doses of vaccination, the humoral immune response rate was similar in CLD patients and healthy controls (risk ratio [RR] = 0.96; 95% CI = 0.90-1.02; p = .14). In contrast, LT recipients had a lower humoral immune response rate after two doses of vaccination than healthy controls (RR = 0.68; 95% CI = 0.59-0.77; p < .01).

CONCLUSIONS

Our meta-analysis demonstrated that COVID-19 vaccination induced strong humoral immune responses in CLD patients but poor humoral immune responses in LT recipients.

SARS-CoV-2 Vaccination in Solid-Organ Transplant Recipients

The coronavirus disease 2019 (COVID-19) pandemic has posed significant global challenges for solid organ transplant (SOT) recipients. Mortality rates of COVID-19 in this patient population remain high, despite new available therapeutic options and Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) vaccination. Priority access to SARS-CoV-2 vaccination for waitlisted candidates and for SOT patients and their family members is recommended since the advantage from vaccination reduces the risk of COVID-19-related complications. However, immunogenicity and efficacy of COVID-19 vaccines are lower in waitlisted candidates and SOT recipients than in the general population. Routine systematic assessment of humoral and cellular immune responses after SARS-CoV-2 vaccination is controversial, although highly recommended for investigation and improvement of knowledge. SOT recipients should continue to adhere to preventive protective measures despite vaccination and may undergo passive antibody prophylaxis. This article seeks to provide an update on SARS-CoV-2 vaccination and preventive measures in SOT recipients based on existing literature and international guidelines.

Seroconversion following the first, second, and third dose of SARS-CoV-2 vaccines in immunocompromised population: a systematic review and meta-analysis

BACKGROUND

Immunocompromised (IC) patients are at higher risk of more severe COVID-19 infections than the general population. Special considerations should be dedicated to such patients. We aimed to investigate the efficacy of COVID-19 vaccines based on the vaccine type and etiology as well as the necessity of booster dose in this high-risk population.

MATERIALS AND METHODS

We searched PubMed, Web of Science, and Scopus databases for observational studies published between June 1st, 2020, and September 1st, 2021, which investigated the seroconversion after COVID-19 vaccine administration in adult patients with IC conditions. For investigation of sources of heterogeneity, subgroup analysis and sensitivity analysis were conducted. Statistical analysis was performed using R software.

RESULTS

According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, we included 81 articles in the meta-analysis. The overall crude prevalence of seroconversion after the first (n: 7460), second (n: 13,181), and third (n: 909, all population were transplant patients with mRNA vaccine administration) dose administration was 26.17% (95% CI 19.01%, 33.99%, I² = 97.1%), 57.11% (95% CI: 49.22%, 64.83%, I² = 98.4%), and 48.65% (95% CI: 34.63%, 62.79%, I² = 94.4%). Despite the relatively same immunogenicity of mRNA and vector-based vaccines after the first dose, the mRNA vaccines induced higher immunity after the second dose. Regarding the etiologic factor, transplant patients were less likely to develop immunity after both first and second dose rather than patients with malignancy (17.0% vs 37.0% after first dose, P = 0.02; 38.3% vs 72.1% after second dose, P < 0.001) or autoimmune disease (17.0% vs 36.4%, P = 0.04; 38.3% vs 80.2%, P < 0.001). To evaluate the efficacy of the third dose, we observed an increasing trend in transplant patients after the first (17.0%), second (38.3%), and third (48.6%) dose.

CONCLUSION

The rising pattern of seroconversion after boosting tends to be promising. In this case, more attention should be devoted to transplant patients who possess the lowest response rate.

Effectiveness of SARS-CoV-2 Vaccines for Short- and Long-Term Immunity: A General Overview for the Pandemic Contrast

Background: The recent COVID-19 pandemic produced a significant increase in cases and an emergency state was induced worldwide. The current knowledge about the COVID-19 disease concerning diagnoses, patient tracking, the treatment protocol, and vaccines provides a consistent contribution for the primary prevention of the viral infection and decreasing the severity of the SARS-CoV-2 disease. The aim of the present investigation was to produce a general overview about the current findings for the COVID-19 disease, SARS-CoV-2 interaction mechanisms with the host, therapies and vaccines’ immunization findings. Methods: A literature overview was produced in order to evaluate the state-of-art in SARS-CoV-2 diagnoses, prognoses, therapies, and prevention. Results: Concerning to the interaction mechanisms with the host, the virus binds to target with its Spike proteins on its surface and uses it as an anchor. The Spike protein targets the ACE2 cell receptor and enters into the cells by using a special enzyme (TMPRSS2). Once the virion is quietly accommodated, it releases its RNA. Proteins and RNA are used in the Golgi apparatus to produce more viruses that are released. Concerning the therapies, different protocols have been developed in observance of the disease severity and comorbidity with a consistent reduction in the mortality rate. Currently, different vaccines are currently in phase IV but a remarkable difference in efficiency has been detected concerning the more recent SARS-CoV-2 variants. Conclusions: Among the many questions in this pandemic state, the one that recurs most is knowing why some people become more seriously ill than others who instead contract the infection as if it was a trivial flu. More studies are necessary to investigate the efficiency of the treatment protocols and vaccines for the more recent detected SARS-CoV-2 variant.

Third COVID-19 vaccine dose boosts neutralizing antibodies in poor responders

Background

While evaluating COVID-19 vaccine responses using a rapid neutralizing antibody (NAb) test, we observed that 25% of mRNA vaccine recipients did not neutralize >50%. We termed this group “vaccine poor responders” (VPRs). The objective of this study was to determine if individuals who neutralized <50% would remain VPRs, or if a third dose would elicit high levels of NAbs.

Methods

269 healthy individuals ranging in age from 19 to 80 (Average age = 51; 165 females and 104 males) who received either BNT162b2 (Pfizer) or mRNA-1273 (Moderna) vaccines were evaluated. NAb levels were measured: (i) 2–4 weeks after a second vaccine dose, (ii) 2–4 months after the second dose, (iii) within 1–2 weeks prior to a third dose and (iv) 2–4 weeks after a third mRNA vaccine dose.

Results

Analysis of vaccine recipients reveals that 25% did not neutralize above 50% (Median neutralization = 21%, titers <1:80) within a month after their second dose. Twenty-three of these VPRs obtained a third dose of either BNT162b2 or mRNA-1273 vaccine 1–8 months (average = 5 months) after their second dose. Within a month after their third dose, VPRs show an average 5.4-fold increase in NAb levels (range: 46–99%).

Conclusions

The results suggest that VPRs are not permanently poor responders; they can generate high NAb levels with an additional vaccine dose. Although it is not known what levels of NAbs protect from infection or disease, those in high-risk professions may wish to keep peripheral NAb levels high, limiting infection, and potential transmission.

Neutralizing antibodies are proteins used by the immune system to respond to viruses and other infectious agents. Vaccination against COVID-19 induces production of neutralizing antibodies that stop virus from infecting cells. We measured levels of neutralizing antibodies in a drop of blood after 2 doses of vaccines distributed by Pfizer and BioNTech or Moderna (COMIRNATY and Spikevax). Twenty-five percent of vaccine recipients did not make high levels of neutralizing antibodies. After receiving a third dose of vaccine, most of these vaccine recipients made high levels of neutralizing antibodies. Our data suggest a third dose is important for vaccine recipients that did not generate high neutralizing antibody levels after 2 doses of vaccine and thus might be an important component of a successful vaccination strategy.

Lake, Roeder et al. measured neutralizing antibody responses after 2 and 3 doses of mRNA COVID vaccination. Recipients who did not generate strong neutralizing antibody responses after 2 vaccine doses were found to have high levels of neutralizing antibodies after a third vaccine dose.

Humoral Response to 2-dose BNT162b2 mRNA COVID-19 Vaccination in Liver Transplant Recipients

BACKGROUND & AIMS

In the context of the Italian severe acute respiratory syndrome coronavirus 2 vaccination program, liver transplant (LT) recipients were prioritized for vaccine administration, although the lower response to vaccines is a well-known problem in this population. We aimed to evaluate immunogenicity of BNT162b2 mRNA vaccine in LT recipients and healthy controls and to identify factors associated with negative response to vaccine.

METHODS

In a cohort of adult patients with LT, we prospectively evaluated the humoral response (with anti-Spike protein IgG-LIAISON SARS-CoV-2 S1/S2-IgG chemiluminescent assay) at 1 and 3 months after 2-dose vaccination. A group of 307 vaccinated health care workers, matched by age and sex, served as controls.

RESULTS

Overall, 492 LT patients were enrolled (75.41% male; median age, 64.85 years). Detectable antibodies were observed in the 75% of patients, with a median value of 73.9 AU/mL after 3 months from 2-dose vaccination. At multivariable analysis, older age (>40 years; P = .016), shorter time from liver transplantation (<5 years; P = .004), and immunosuppression with antimetabolites (P = .029) were significantly associated with non-response to vaccination. Moreover, the LT recipients showed antibody titers statistically lower than the control group (103 vs 261 AU/mL; P < .0001). Finally, in both controls and LT patients, we found a trend of inverse correlation between age and antibody titers (correlation coefficients: -0.2023 and -0.2345, respectively).

CONCLUSIONS

Three months after vaccination, LT recipients showed humoral response in 75% of cases. Older age, shorter time from transplantation, and use of antimetabolites were factors associated with non-response to vaccination, and LT recipients at risk of non-response to vaccination needed to be kept under close monitoring.

Risk Factors for Weak Antibody Response of SARS-CoV-2 Vaccine in Adult Solid Organ Transplant Recipients: A Systemic Review and Meta-Analysis

Objective

This is the first systematic review and meta-analysis to determine the factors that contribute to poor antibody response in organ transplant recipients after receiving the 2-dose severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine.

Method

Data was obtained from Embase, PubMed, Web of Science, Cochrane Library, China National Knowledge Infrastructure (CNKI), and Chinese Biomedical Literature Database (CBM). Studies reporting factors associated with antibody responses to the 2-dose SARS-CoV-2 vaccine in solid organ transplant recipients were included in our study based on the inclusion and exclusion criteria. Two researchers completed the literature search, screening, and data extraction. Randomized models were used to obtain results. Egger’s test was performed to determine publication bias. Sensitivity analysis was performed to determine the stability of the result. The heterogeneity was determined using the Galbraith plot and subgroup analysis.

Results

A total of 29 studies were included in the present study. The factors included living donor, BNT162b2, tacrolimus, cyclosporine, antimetabolite, mycophenolic acid (MPA) or mycophenolate mofetil (MMF), azathioprine, corticosteroids, high-dose corticosteroids, belatacept, mammalian target of rapamycin (mTOR) inhibitor, tritherapy, age, estimated glomerular filtration rate (eGFR), hemoglobin, and tacrolimus level were significantly different. Multivariate analysis showed significant differences in age, diabetes mellitus, MPA or MMF, high-dose corticosteroids, tritherapy, and eGFR.

Conclusion

The possible independent risk factors for negative antibody response in patients with organ transplants who received the 2-dose SARS-CoV-2 vaccine include age, diabetes mellitus, low eGFR, MPA or MMF, high-dose corticosteroids, and triple immunosuppression therapy. mTOR inhibitor can be a protective factor against weak antibody response.

Systematic Review Registration

PROSPERO, identifier CRD42021257965.

Immunogenicity and safety of a third dose of anti-SARS-CoV-2 BNT16b2 vaccine in liver transplant recipients

BACKGROUND & AIMS

A strategy to improve the low rate of anti-SARS-CoV-2 mRNA vaccine-induced immunogenicity in liver transplant recipients (LTs) is urgently needed.

METHODS

We analysed the rate of positive (≥0.8 U/ml) anti-SARS-CoV-2 receptor domain-binding protein (RBD) antibody response 2 months after a third dose of the BNT16b2 vaccine in 107 LTs who completed the second vaccine dose 7 months earlier.

RESULTS

A positive anti-SARS-CoV-2-s-RBD antibody response after the third vaccine dose was detected in 98 (91.6%) LTs compared to 82 (76.6%) after the second vaccine dose (p = .003). The median of anti-SARS-CoV-2 RBD antibody titres increased from 22.9 U/ml 6 months after the second to 3500 U/ml 2 months after the third vaccine dose (p < .001). Fourteen (14.3%) responder patients presented antibody titres <100 U/ml, 57 (58.2%) between 100 and 9999 U/ml and 27 (27.6%) ≥10 000 U/ml. Seropositivity after the second dose was maintained after the third dose. Independent predictors of antibody response failure after the third vaccine dose were taking a higher daily dose of mycophenolate mofetil (MMF, p < .001) and had a lower (<60 ml/min/1.73 m² ) estimated glomerular filtration rate (p = .007). Nine (9.1%) LTs experienced symptomatic SARS-CoV-2 infection after the third vaccine dose. Median antibody titres were not statistically different between infected and not infected LTs (1325 vs 3515 U/ml, p = .678).

CONCLUSIONS

The third dose of the BNT16b2 vaccine increased the number of LTs who developed a positive anti-SARS-CoV-2 s-RBD antibody response. A proportion of patients remained unresponsive, mainly for modifiable factors, such as the use of MMF or multiple immunosuppressants.

Humoral immunity against SARS-CoV-2 variants including omicron in solid organ transplant recipients after three doses of a COVID-19 mRNA vaccine

Objectives

Solid organ transplant recipients (SOTR) receiving post‐transplant immunosuppression show increased COVID‐19‐related mortality. It is unclear whether an additional dose of COVID‐19 vaccines can overcome the reduced immune responsiveness against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) variants.

Methods

We analysed humoral immune responses against SARS‐CoV‐2 and its variants in 53 SOTR receiving SARS‐CoV‐2 vaccination.

Results

Following the initial vaccination series, 60.3% of SOTR showed no measurable neutralisation and only 18.9% demonstrated neutralising activity of > 90%. More intensive immunosuppression, antimetabolites in particular, negatively impacted antiviral immunity. While absolute IgG levels were lower in SOTR than controls, antibody titres against microbial recall antigens were higher. By contrast, SOTR showed reduced vaccine‐induced IgG/IgA antibody titres against SARS‐CoV‐2 and its delta variants and fewer linear B‐cell epitopes, indicating reduced B‐cell diversity. Importantly, a third vaccine dose led to an increase in anti‐SARS‐CoV‐2 antibody titres and neutralising activity across alpha, beta and delta variants and to the induction of anti‐SARS‐CoV‐2 CD4⁺ T cells in a subgroup of patients analysed. By contrast, we observed significantly lower antibody titres after the third dose with the omicron variant compared to the ancestral SARS‐CoV‐2 and the improvement in neutralising activity was much less pronounced than for all the other variants.

Conclusion

Only a small subgroup of solid organ transplant recipients is able to generate functional antibodies after an initial vaccine series; however, an additional vaccine dose resulted in dramatically improved antibody responses against all SARS‐CoV‐2 variants except omicron where antibody responses and neutralising activity remained suboptimal.

COVID-19 vaccine development: milestones, lessons and prospects

With the constantly mutating of SARS-CoV-2 and the emergence of Variants of Concern (VOC), the implementation of vaccination is critically important. Existing SARS-CoV-2 vaccines mainly include inactivated, live attenuated, viral vector, protein subunit, RNA, DNA, and virus-like particle (VLP) vaccines. Viral vector vaccines, protein subunit vaccines, and mRNA vaccines may induce additional cellular or humoral immune regulations, including Th cell responses and germinal center responses, and form relevant memory cells, greatly improving their efficiency. However, some viral vector or mRNA vaccines may be associated with complications like thrombocytopenia and myocarditis, raising concerns about the safety of these COVID-19 vaccines. Here, we systemically assess the safety and efficacy of COVID-19 vaccines, including the possible complications and different effects on pregnant women, the elderly, people with immune diseases and acquired immunodeficiency syndrome (AIDS), transplant recipients, and cancer patients. Based on the current analysis, governments and relevant agencies are recommended to continue to advance the vaccine immunization process. Simultaneously, special attention should be paid to the health status of the vaccines, timely treatment of complications, vaccine development, and ensuring the lives and health of patients. In addition, available measures such as mix-and-match vaccination, developing new vaccines like nanoparticle vaccines, and optimizing immune adjuvant to improve vaccine safety and efficacy could be considered.

Patients After Orthotopic Heart Transplantation With COVID-19: Are We Fast Enough With Vaccinations?

BACKGROUND

Patients after orthotopic heart transplantation (HTx) are especially susceptible to infections owing to permanent need for immunosuppression. Vaccinations against COVID-19 have been available since January 2021 and are recommended in organ recipients.

AIM

The aim of this study was to analyze COVID-19 susceptibility and mortality in HTx and number of patients with COVID-19 previously vaccinated against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

PATIENTS AND METHODS

We analyzed a whole cohort of 552 patients after HTx who were SARS-CoV-2 positive and remained under surveillance of the transplantation center during March 2020 to September 2021.

RESULTS

Among 552 patients after HTx, 10 were COVID-19 survivors prior to transplantation and 103 had SARS CoV-2 infection after transplantation. Mean age of patients with COVID-19 was 55.6 (±14) years, and mean time from transplantation to SARS-CoV-2 infection was 2856 (±2596) days (range, 16-9569 days; interquartile range, 397-4763 days). Among the patients who were COVID-19 positive, 15 were asymptomatic, 10 died, and 51 infections occurred in the era of vaccinations. In the group of patients who were positive for COVID-19 in 2021, 6 received only a single dose of the mRNA vaccine and 3 were vaccinated twice. Among the vaccinated patients with COVID-19, 2 died of severe COVID-19: 1 after a single dose and 1 after 2 standard doses of the vaccine.

CONCLUSION

We observed high susceptibility to SARS-CoV-2 infection in the group of patients after HTx. The majority of patients infected in 2021 did not received the vaccine. Vaccination does not fully protect against severe COVID-19 in patients after HTx.

Decline in Antibody Concentration 6 Months After Two Doses of SARS-CoV-2 BNT162b2 Vaccine in Solid Organ Transplant Recipients and Healthy Controls

Background

Previous studies have indicated inferior responses to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) vaccination in solid organ transplant (SOT) recipients. We examined the development of anti-receptor-binding domain (RBD) immunoglobulin G (IgG) after two doses of BNT162b2b in SOT recipients 6 months after vaccination and compared to that of immunocompetent controls.

Methods

We measured anti-RBD IgG after two doses of BNT162b2 in 200 SOT recipients and 200 matched healthy controls up to 6 months after first vaccination. Anti-RBD IgG concentration and neutralizing capacity of antibodies were measured at first and second doses of BNT162b2 and 2 and 6 months after the first dose. T-cell responses were measured 6 months after the first dose.

Results

In SOT recipients, geometric mean concentration (GMC) of anti-RBD IgG increased from first to second dose (1.14 AU/ml, 95% CI 1.08–1.24 to 11.97 AU/ml, 95% CI 7.73–18.77) and from second dose to 2 months (249.29 AU/ml, 95% CI 153.70–385.19). Six months after the first vaccine, anti-RBD IgG declined (55.85 AU/ml, 95% CI 36.95–83.33). At all time points, anti-RBD IgG was lower in SOT recipients than that in controls. Fewer SOT recipients than controls had a cellular response (13.1% vs. 59.4%, p < 0.001). Risk factors associated with humoral non-response included age [relative risk (RR) 1.23 per 10-year increase, 95% CI 1.11–1.35, p < 0.001], being within 1 year from transplantation (RR 1.55, 95% CI 1.30–1.85, p < 0.001), treatment with mycophenolate (RR 1.54, 95% CI 1.09–2.18, p = 0.015), treatment with corticosteroids (RR 1.45, 95% CI 1.10–1.90, p = 0.009), kidney transplantation (RR 1.70, 95% CI 1.25–2.30, p = 0.001), lung transplantation (RR 1.63, 95% CI 1.16–2.29, p = 0.005), and de novo non-skin cancer comorbidity (RR 1.52, 95% CI, 1.26–1.82, p < 0.001).

Conclusion

Immune responses to BNT162b2 are inferior in SOT recipients compared to healthy controls, and studies aiming to determine the clinical impact of inferior vaccine responses are warranted.

Efficacy of covid-19 vaccines in immunocompromised patients: systematic review and meta-analysis

OBJECTIVE

To compare the efficacy of covid-19 vaccines between immunocompromised and immunocompetent people.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Embase, Central Register of Controlled Trials, COVID-19 Open Research Dataset Challenge (CORD-19), and WHO covid-19 databases for studies published between 1 December 2020 and 5 November 2021. ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform were searched in November 2021 to identify registered but as yet unpublished or ongoing studies.

STUDY SELECTION

Prospective observational studies comparing the efficacy of covid-19 vaccination in immunocompromised and immunocompetent participants.

METHODS

A frequentist random effects meta-analysis was used to separately pool relative and absolute risks of seroconversion after the first and second doses of a covid-19 vaccine. Systematic review without meta-analysis of SARS-CoV-2 antibody titre levels was performed after first, second, and third vaccine doses and the seroconversion rate after a third dose. Risk of bias and certainty of evidence were assessed.

RESULTS

82 studies were included in the meta-analysis. Of these studies, 77 (94%) used mRNA vaccines, 16 (20%) viral vector vaccines, and 4 (5%) inactivated whole virus vaccines. 63 studies were assessed to be at low risk of bias and 19 at moderate risk of bias. After one vaccine dose, seroconversion was about half as likely in patients with haematological cancers (risk ratio 0.40, 95% confidence interval 0.32 to 0.50, I²=80%; absolute risk 0.29, 95% confidence interval 0.20 to 0.40, I²=89%), immune mediated inflammatory disorders (0.53, 0.39 to 0.71, I²=89%; 0.29, 0.11 to 0.58, I²=97%), and solid cancers (0.55, 0.46 to 0.65, I²=78%; 0.44, 0.36 to 0.53, I²=84%) compared with immunocompetent controls, whereas organ transplant recipients were 16 times less likely to seroconvert (0.06, 0.04 to 0.09, I²=0%; 0.06, 0.04 to 0.08, I²=0%). After a second dose, seroconversion remained least likely in transplant recipients (0.39, 0.32 to 0.46, I²=92%; 0.35, 0.26 to 0.46), with only a third achieving seroconversion. Seroconversion was increasingly likely in patients with haematological cancers (0.63, 0.57 to 0.69, I²=88%; 0.62, 0.54 to 0.70, I²=90%), immune mediated inflammatory disorders (0.75, 0.69 to 0.82, I²=92%; 0.77, 0.66 to 0.85, I²=93%), and solid cancers (0.90, 0.88 to 0.93, I²=51%; 0.89, 0.86 to 0.91, I²=49%). Seroconversion was similar between people with HIV and immunocompetent controls (1.00, 0.98 to 1.01, I²=0%; 0.97, 0.83 to 1.00, I²=89%). Systematic review of 11 studies showed that a third dose of a covid-19 mRNA vaccine was associated with seroconversion among vaccine non-responders with solid cancers, haematological cancers, and immune mediated inflammatory disorders, although response was variable in transplant recipients and inadequately studied in people with HIV and those receiving non-mRNA vaccines.

CONCLUSION

Seroconversion rates after covid-19 vaccination were significantly lower in immunocompromised patients, especially organ transplant recipients. A second dose was associated with consistently improved seroconversion across all patient groups, albeit at a lower magnitude for organ transplant recipients. Targeted interventions for immunocompromised patients, including a third (booster) dose, should be performed.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42021272088.

Serologic status according SARS-CoV-2 in patients after orthotopic heart transplantation (HTx)

Background

The SARS-CoV-2 pandemic is ongoing. In this context, patients after organ transplantation are especially endangered because of their increased susceptibility to infections. Real effectiveness of vaccinations against SARS-CoV-2 and exposition to the virus in populations after organ transplantation is still being assessed.

Methods

We investigated 371 adult patients (82.7% men, 17.3% women), aged 54 ± 14 years, with a median time from transplantation of 1296 days (interquartile range, 473-400 days) after orthotopic heart transplantation consecutively admitted to the transplant center between February and September 2021. SARS-CoV-2 spike protein antibodies were assessed quantitatively by Elecsys Anti-SARS-CoV-2 S. Data according to past COVID-19 infection and vaccination were compared with the test results.

Among the whole group, 59 patients were unvaccinated and had no past COVID-19 infection, 200 patients had a full course of vaccination (2 doses) with an mRNA vaccine, 1 patient had received a viral vector vaccine, 11 patients had had a single dose of an mRNA vaccine, and 99 patients had previously had a COVID-19 infection. Median time from vaccination to antibody assessment was 54 days (interquartile range, 30-76 days).

Aim

The aim of this study was to determine exposure to the virus among patients after heart transplantation before vaccination and humoral response to the vaccination and assess the role of antispike antibodies in the prevention of infection.

Results

After vaccination, 22.3% had no antibodies (45 patients), 47.3% had titers between 0.8 U/mL [0.82 binding antibody units (BAU)/mL] and 250 U/mL (257.25 BAU/mL; 95 patients), and 30.2% had titers above 250 U/mL (257.25 BAU/mL; 61 patients). After a single dose of vaccine, 63% patients had no antibodies. In the group of unvaccinated patients, 3 patients had titers above 250 U/mL (257.25 BAU/mL; 5.1%) and 12 patients had titers up to 250 U/mL (257.25 BAU/mL; 20.3%).

In patients after COVID-19 infection, only 2% did not show antispike antibodies, and in 61.4% the titers were above 250 U/mL (257.25 BAU/mL).

In the group of patients infected after the full course of vaccination (4 patients after a single dose and 2 after 2 doses), none of the patients developed antibodies after vaccination. Up to the end of September 2021, none of the patients with antibodies against SARS-CoV-2 developed COVID-19.

Conclusions

The presence of spike protein antibodies may be a relevant marker of effective vaccination. In patients after heart transplantation, exposure to SARS-CoV-2 is high.

Fighting the SARS-CoV-2 pandemic requires a global approach to understanding the heterogeneity of vaccine responses

Host genetic and environmental factors including age, biological sex, diet, geographical location, microbiome composition and metabolites converge to influence innate and adaptive immune responses to vaccines. Failure to understand and account for these factors when investigating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine efficacy may impair the development of the next generation of vaccines. Most studies aimed at identifying mechanisms of vaccine-mediated immune protection have focused on adaptive immune responses. It is well established, however, that mobilization of the innate immune response is essential to the development of effective cellular and humoral immunity. A comprehensive understanding of the innate immune response and environmental factors that contribute to the development of broad and durable cellular and humoral immune responses to SARS-CoV-2 and other vaccines requires a holistic and unbiased approach. Along with optimization of the immunogen and vectors, the development of adjuvants based on our evolving understanding of how the innate immune system shapes vaccine responses will be essential. Defining the innate immune mechanisms underlying the establishment of long-lived plasma cells and memory T cells could lead to a universal vaccine for coronaviruses, a key biomedical priority.

Immunological and clinical efficacy of COVID-19 vaccines in immunocompromised populations: a systematic review

BACKGROUND

Available data show that COVID-19 vaccines may be less effective in immunocompromised populations, who are at increased risk of severe COVID-19.

OBJECTIVES

We conducted a systematic review of literature to assess immunogenicity, efficacy and effectiveness of COVID-19 vaccines in immunocompromised populations.

DATA SOURCES

We searched Medline and Embase databases.

STUDY ELIGIBILITY CRITERIA, PATIENTS, INTERVENTIONS

We included studies of COVID-19 vaccines after complete vaccination in immunocompromised patients until 31 August 2021. Studies with <10 patients, safety data only and case series of breakthrough infections were excluded.

METHODS

Risk of bias was assessed via the tool developed by the National Institutes of Health on interventional and observational studies. Immunogenicity was assessed through non-response rate defined as no anti-SARS-CoV-2 spike protein antibodies, efficacy and effectiveness by the relative reduction in risk of SARS-CoV-2 infection or COVID-19. We collected factors associated with the risk of non-response. We presented collected data by immunosuppression type.

RESULTS

We screened 5917 results, included 162 studies. There were 157 on immunogenicity in 25 209 participants, including 7835 cancer or haematological malignancy patients (31.1%), 6302 patients on dialysis (25.0%), 5974 solid organ transplant recipients (23.7%) and 4680 immune-mediated disease patients (18.6%). Proportion of non-responders seemed higher among solid organ transplant recipients (range 18-100%) and patients with haematological malignancy (range 14-61%), and lower in patients with cancer (range 2-36%) and patients on dialysis (range 2-30%). Risk factors for non-response included older age, use of corticosteroids, immunosuppressive or anti-CD20 agent. Ten studies evaluated immunogenicity of an additional dose. Five studies evaluated vaccine efficacy or effectiveness: three on SARS-CoV-2 infection (range 71-81%), one on COVID-19-related hospitalization (62.9%), one had a too small sample size.

CONCLUSIONS

This systematic review highlights the risk of low immunogenicity of COVID-19 vaccines in immunocompromised populations, especially solid organ transplant recipients and patients with haematological malignancy. Despite lack of vaccine effectiveness data, enhanced vaccine regimens may be necessary.

SARS-CoV-2-specific T cells generated for adoptive immunotherapy are capable of recognizing multiple SARS-CoV-2 variants

Adoptive T-cell immunotherapy has provided promising results in the treatment of viral complications in humans, particularly in the context of immunocompromised patients who have exhausted all other clinical options. The capacity to expand T cells from healthy immune individuals is providing a new approach to anti-viral immunotherapy, offering rapid off-the-shelf treatment with tailor-made human leukocyte antigen (HLA)-matched T cells. While most of this research has focused on the treatment of latent viral infections, emerging evidence that SARS-CoV-2-specific T cells play an important role in protection against COVID-19 suggests that the transfer of HLA-matched allogeneic off-the-shelf virus-specific T cells could provide a treatment option for patients with active COVID-19 or at risk of developing COVID-19. We initially screened 60 convalescent individuals and based on HLA typing and T-cell response profile, 12 individuals were selected for the development of a SARS-CoV-2-specific T-cell bank. We demonstrate that these T cells are specific for up to four SARS-CoV-2 antigens presented by a broad range of both HLA class I and class II alleles. These T cells show consistent functional and phenotypic properties, display cytotoxic potential against HLA-matched targets and can recognize HLA-matched cells infected with different SARS-CoV-2 variants. These observations demonstrate a robust approach for the production of SARS-CoV-2-specific T cells and provide the impetus for the development of a T-cell repository for clinical assessment.

Since the emergence of SARS-CoV-2 variants that reduce the effectiveness of vaccines, it is evident that other interventional strategies will be needed to treat COVID-19, particularly in patients with a compromised immune system who are at an increased risk of developing severe COVID-19. Off-the-shelf T-cell immunotherapy is proving to be a powerful tool to treat viral disease in patients with a compromised immune system. Here, we report here that a small number of SARS-CoV-2 exposed individuals can be used generate a bank of specific T cells that provide broad population coverage. Importantly, we demonstrate that most of the epitopes recognized by these T cells remain unchanged in different variants and that the T cells can recognize cells infected with three different variants of SARS-CoV-2. We believe these observations provide critical proof-of-concept that T-cell based immunotherapy may offer an option for the future treatment of immunocompromised patients who remain susceptible to the severe complications associated with COVID-19.

Spike Gene Evolution and Immune Escape Mutations in Patients with Mild or Moderate Forms of COVID-19 and Treated with Monoclonal Antibodies Therapies

We explored the molecular evolution of the spike gene after the administration of anti-spike monoclonal antibodies in patients with mild or moderate forms of COVID-19. Four out of the 13 patients acquired a mutation during follow-up; two mutations (G1204E and E406G) appeared as a mixture without clinical impact, while the Q493R mutation emerged in two patients (one receiving bamlanivimab and one receiving bamlanivimab/etesevimab) with fatal outcomes. Careful virological monitoring of patients treated with mAbs should be performed, especially in immunosuppressed patients.

SARS-CoV-2 Vaccines: Safety and Immunogenicity in Solid Organ Transplant Recipients and Strategies for Improving Vaccine Responses

Purpose of Review

While solid organ transplant (SOT) recipients are at the highest risk for severe complications and increased mortality from COVID19 disease, their vaccination against SARS-CoV-2 remains challenging due to fear of immune-mediated adverse events and suboptimal immune response. Our current review is aimed to summarize current knowledge about the safety and efficacy of SARS-CoV-2 vaccines, describe factors that are correlated with immune response, and discuss strategies to improve vaccine immunogenicity in SOT recipients.

Recent Findings

SARS-CoV-2 vaccines are safe in SOT recipients and not related to rejection or other major adverse events. The immune response to two doses of vaccine is suboptimal and correlated to age and magnitude of immunosuppression. Administration of a third vaccine dose brings to significant amplification of immune response.

Summary

This review strengthens the existing recommendation of vaccination by three doses of vaccine in all SOT recipients and completion of vaccination before transplantation if possible.

Two Doses of BNT162b2 mRNA Vaccine in Patients after Hematopoietic Stem Cell Transplantation: Humoral Response and Serological Conversion Predictors

Simple Summary

Vaccination against SARS-CoV-2 is currently the best tool in the fight against the COVID-19 pandemic. However, there are concerns about its efficacy and safety after hematopoietic stem cell transplantation. The aim of the study was to study the efficacy and safety of two doses of BNT162b2 mRNA vaccine in adult patients after autologous or allogeneic transplantation. We examined the presence of anti-SARS-CoV-2 antibodies before and after vaccination. We also searched for the potential predictors of serological conversion after vaccination, including the analysis of the impact of various lymphocyte subpopulations at the time of vaccination on post-vaccine antibody concentration and seroconversion. In addition, patients were followed-up for adverse events after vaccination, and the data on breakthrough SARS-CoV-2 infection were collected. The results of our study broaden the knowledge of the efficacy and safety of BNT162b2 mRNA vaccine in patients after HCT, providing new data on serological conversion predictors.

Abstract

Vaccination against SARS-CoV-2 is currently the best tool in the fight against the COVID-19 pandemic. However, there are limited data on its efficacy and safety after hematopoietic stem cell transplantation (HCT). We present the results of a prospective analysis of the humoral response to two doses of BNT162b2 mRNA vaccine in 93 adult patients, including 29 after autologous HCT (autoHCT) and 64 after allogeneic HCT (alloHCT). Positive anti-SARS-CoV-2 antibodies were detected before vaccination in 25% of patients despite a negative medical history of COVID-19. Seroconversion after vaccination was achieved in 89% of patients after alloHCT and in 96% after autoHCT, without grade 3/4 adverse events. Post-vaccination anti-SARS-CoV-2 antibody level correlated with the time from transplant and absolute B-cell count at the vaccination. In univariate analysis restricted to the alloHCT group, short time since transplantation, low B-cell count, low intensity conditioning, GvHD, and immunosuppressive treatment at the vaccination were associated with lack of seroconversion. In the multivariate model, the only negative predictor of seroconversion remained treatment with calcineurin inhibitor (CNI). In conclusion, the BNT162b2 mRNA vaccine is highly immunogenic in patients after HCT, but treatment with CNI at the time of vaccination has a strong negative impact on the humoral response

Humoral Immune Response to SARS-CoV-2 Vaccination after a Booster Vaccine Dose in Two Kidney Transplant Recipients with Fabry Disease and Variable Secondary Immunosuppressive Regimens

The urgent need to fight the COVID-19 pandemic has accelerated the development of vaccines against SARS-CoV-2 and approval processes. Initial analysis of two-dose regimens with mRNA vaccines reported up to 95% efficacy against the original strain of the SARS-CoV-2 virus. Challenges arose with the appearance of new strains of the virus, and reports that solid organ transplant recipients may have reduced vaccination success rates after a two-dose mRNA vaccination regimen encouraged health authorities to recommend a booster in immunocompromised patients. Fabry disease is an X-linked inherited lysosomal disorder, which may lead to chronic end-stage renal disease. We report on two patients with advanced Fabry disease, renal graft and adjunctive immunosuppressive therapies who exhibited variable humoral vaccination-related immune responses against SARS-CoV-2 after three vaccine doses. The first patient developed mild COVID-19 infection, while the second patient did not seroconvert after three shots of an mRNA vaccine. Both cases emphasize that patients with Fabry disease and renal graft are susceptible to develop a weak response to COVID-19 vaccination and highlight the importance of maintaining barrier protection measures. Vaccination of family members should be encouraged to lower the risk of viral transmission to immunocompromised, transplanted patients, including vaccinated ones.

Vaccination against SARS-CoV-2 in Patients with Inflammatory Bowel Diseases: Where Do We Stand?

Crohn’s disease and ulcerative colitis are chronic inflammatory bowel diseases (IBDs). Immunosuppressive medication is the main therapeutic approach to reducing inflammation of the gastrointestinal tract. Immunocompromised patients are more vulnerable to severe courses of illness after infection with common pathogens. The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the pathogen of the coronavirus disease 2019 (COVID-19) pandemic. COVID-19 leads to acute respiratory distress syndrome (ARDS) following severe pulmonal damage in a significant number of cases. The worldwide circulation of SARS-CoV-2 has led to major concerns about the management of IBD patients during the pandemic, as these patients are expected to be at greater risk of complications because of their underlying altered immunological condition and immunosuppressive therapies. Vaccination against SARS-CoV-2 is considered the main approach in containing the pandemic. Today, several vaccines have been shown to be highly effective in the prevention of SARS-CoV-2 infection and severe disease course in subjects without underlying conditions in respective registration studies. Patients with underlying conditions such as IBD and/or immunosuppressive therapies were not included in the registration studies, so little is known about effectiveness and safety of SARS-CoV-2 vaccination in immunocompromised IBD patients. This review provides an overview of the recent knowledge about vaccine response in IBD patients after vaccination against SARS-CoV-2.